A myriad of different clinical analysis methods for detecting the presence or absence of various classes of molecules (analytes) have been developed. These analysis methods are used widely in the biological field in detecting the presence of such molecules as proteins and other biomolecules. Proteins have been mainly analyzed by immunoassays such as RIA or ELISA format, DNA by gel or capillary electrophoresis after PCR amplification, small molecules such as glucose and cholesterol, by various color reactions, either chemical or enzymatic, and electrolytes such as sodium or chloride by ion sensitive electrodes. Recently, biochip or biodisc arrays have been developed for protein and DNA analysis. Instrumentation is widely different depending on the application.
In clinical laboratories and large hospitals hundreds of samples are processed with expensive and large automated analyzers. Smaller analyzers, such as microtiter well plate readers, are used in medium or small laboratories. The fastest growing market is the point-of-care (POC) market. Glucose and HCG (pregnancy test) are examples of well established tests in which, typically, strips or dipsticks are used. Although a glucose test by necessity is quantitative, strip tests are qualitative or semi-quantitative at best with very limited dynamic range. The current technology does not allow quantitative assays in vivo, except for oxygen and possibly for glucose.
In all tests in which analyzers are used, the sample is taken first in a separate container such as a syringe or test tube or placed on a strip. Before actual assay, an aliquot of a sample or the strip is transferred into an analyzer. Transfer adds an inconvenient and potentially harmful step, because laboratory personnel can be exposed to pathogens. Although this problem has partially been solved by a cassette and applicator instrument designed for an optical disc based assay, even then a cassette must be inserted into an optical disc.
It would be highly preferable if a sampling device, the syringe or cassette, would be able to perform the actual assay immediately without any further transfer of a sample. Furthermore, it would be desirable to perform tens, or even hundreds, of different assays for various classes of analytes from the same sample. The instrument may be disposable, and of low cost.